“This seems to be arson,” Jens Møller, of the Copenhagen Police, told media.

Møller said that fire investigators had identified two sites, about ten metres apart, on the outside of the wooden building where the blaze appears to have started.

Yesterday investigators said the fire had started in a portable toilet, but concluded today that there was nothing to indicate that it began there.

The building, built in 1995 and which housed the country's largest collection of Second World War items, was destroyed in the fire that took Copenhagen firefighters 10 hours to extinguish. Miraculously, most of the museum's collection was removed from the building before suffering permanent fire or water damage.

Police have no suspects at this point and are asking anyone who may have information that could help lead to an arrest to contact them.

According to the culture minister, Marianne Jelved, the museum, which is a part of the National Museum, will be rebuilt.